A customs declaration is a document that a customer must submit to the Czech Customs Administration when ordering goods from countries outside the European Union. The declaration can be submitted even before the parcel physically arrives in the Czech Republic, as soon as the parcel's tracking number is known.

In some cases, the end customer is not required to submit the customs declaration themselves — it may be handled by the online shop or the shipping company instead. Zásilkovna supports e-shops with customs declarations so that this obligation does not fall on the customer. To use this service, it is sufficient to request an EORI number.